An international health alliance working to develop a vaccine against malaria says one of its most advanced vaccines, called RTS,S, shows promising results. After two years of human clinical trials in Africa, the PATH Malaria Vaccine Initiative and its collaborators report the vaccine provides protection against malaria for children aged five to 17 months.

Scientists working on the world’s first-ever malaria vaccine are calling the RTS,S trials a significant milestone.

“For 40 years people have been trying to develop malaria vaccine and here we are,” said Dr. Christian Loucq, the director of Malaria Vaccine Initiative, which is an international non-profit group involved in assessing the safety and effectiveness of the new vaccine. Thousands of children in seven countries in Africa received the vaccine. Investigators found that in vaccinated children, the risk of severe and clinical malaria was reduced by half.

“Phase Three is where you look into efficacy and safety for which we had consistent results and we are very happy and encouraged to move on,” said Dr. Daniel Ansong, a pediatrician and researcher at one of the clinical-trial sites in Ghana.

Dr. Ansong believes the vaccine will be a valuable new weapon in the global war on malaria.

Critics note that in the field trials, the new vaccine was only 47 percent effective against severe malaria, a level of protection they say should be higher. But pediatricians say that with malaria killing 800,000 children every year, even this level of efficacy could save thousands of lives.

Dr. Joe Cohen is co-inventor of the RTS,S vaccine and a researcher at the drug companty GlaxoSmith-line. It has invested $300 million in malaria vaccine development.

Cohen says developing a vaccine against malaria has been a major scientific challenge. “The problem, I think, is the parasite itself. Malaria parasite - parasites in general - very complex organisms, with complex DNA makeup with many thousands of genes, in contrast to bacteria or viruse,” he said.

GlaxoSmith-Kline says it expects to invest an additional $50 to 100 million in the vaccine program. Researchers say they will start testing the vaccine on larger populations after the successful completion of ongoing Phase Three trials.

The developers plan to submit the final results of the vaccine trials to the World Health Organization by 2014. Their hope is that the WHO will recommend that the malaria vaccine become a routine part of all future childhood immunization programs.